Abstract: A three part split shaft seal assembly is disclosed which is particularly adapted for use in an overhung steam turbine. In one embodiment the assembly is located between the shaft opening of the turbine case and a horizontally split shaft bearing case. To facilitate axial insertion and removal of the assembly, the seal assembly is formed from three pairs of split ring seals. Proper axial alignment is maintained by stand-offs or dowel pins located between two of the split ring seals. In one embodiment a snap ring received within an annular groove in the turbine housing holds two of the seal rings against axial movement. In that embodiment set screws carried in one ring seal are used to seat and align two ring seals of the assembly relative to the turbine casing. A pin holds two of the ring seals against relative rotational movement. In another embodiment, a split spacer ring is used to maintain correct spacing and the third seal is used to position and hold the other two seals axially aligned to each other.